A Debreceni Déri Múzeum Évkönyve 1986 (Debrecen, 1987)

Természettudomány - Juhász, Lajos–Bozsko, Szvetlana: The Ornithofauna of Debrecen II. Synecological Analysis

bility estimate obtained from either of these formulae is equal 1.0, the interpretation must be that all of the observed variation in the trait tested in due to heredity. If the estimate is 0.0, all of the variability must be due to environment, or at least it must be assumed that the majority of people in the population from which the sample was drawn are susceptible or posses the ability to react to some common environmental agents, or stimuli. As might be expected, these two extreme values are rarely met in actual experience and the problem is usually one of interpreting intermediate values. Osborne and De George (1959) made metric examinations on 112 healthy twin pairs from the USA, all above the age of 18 years and all being the representatives of the Europid major race (Table 1). Table 1. Mean ages of twins, studied by Osborne and De George (1959) Zygoticity n x s.d. s. e. Monozygotic Males 25 25.8 8.84 1.77 Females 34 26.1 7.94 1.36 Dizygotic Males 10 23.6 5.05 1.60 Females 27 27.1 9.82 1.89 Unlike sex 16 26.1 8.30 2.07 It is obvious then that it would be more expedient to demonstrate our attempt on the sample of the females for as regards this sex the results are much more representative (n:35<6l). On the sample mentioned the authors examined numerous Äeai/-measurements, of which only few can be projected on the ^«//-measurements. Above all 6 measurements can be adapted for such a comparison of osteological series in which the heritability estimated through the variances can also be regarded (Table 2). Table 2. The variance of the 6 examined measurements (Osborne and De George 1959) and their heritability (Penrose 1949, Neel and Schull 1954) Measurements (M No)* Variance DZ Variance MZ Heritability 1. Head length (Ml) 2. Head breadth (M8) 3. Minimal frontal breadth (M9) 4. Bizygomatic breadth (M45) 5. Upper face height (M48) 6. Bigonial breadth (M66) 0.211 (26) 0.169 (27) 0.089 (27) 0.106 (27) 0.107 (27) 0.139 (27) 0.098 (34) 0.041 (34) 0.040 (34) 0.034 (34) 0.030 (34) 0.035 (34) 0.5355 0.7574 0.5506 0.6792 0.7196 0.7482 The appropriate measurement the skull is signed by Martin=M (1928)'s number. Subsequently cluster analyses were accomplished on a chosen sample (see in chapter 3) in two respects: (1) first it was carried out relying merely on the skull measurements experienced, (2) then relying on the measurement weighted by the heritability values. 74